Minor build fix
diff --git a/src/Makefile.am b/src/Makefile.am
index df99afe..4140cbc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -99,6 +99,9 @@
 HBCFLAGS += -I$(srcdir)/hb-ucdn
 HBLIBS   += hb-ucdn/libhb-ucdn.la
 HBSOURCES += $(HB_UCDN_sources)
+hb-ucdn/libhb-ucdn.la: ucdn
+ucdn:
+	@$(MAKE) $(AM_MAKEFLAGS) -C hb-ucdn
 endif
 DIST_SUBDIRS += hb-ucdn